Demulsifiers for mixtures of middle distillates with fuel oils of vegetable or animal origin

ABSTRACT

The invention provides fuel oils comprising a major proportion of a mixture of  
     A) a middle distillate fuel oil, and  
     B) a biofuel oil, and also a minor proportion of  
     C) an oil-soluble copolymer of ethylene and at least 0.2 to 35 mol % of a further olefinically unsaturated compound which contains at least one free hydroxyl group, and which has an OH number of from 10 to 300 mg KOH/g.

[0001] The present invention relates to the use of an additive as ademulsifier for mixtures of middle distillates with vegetable or animalfuel oils and correspondingly additized fuel oils.

[0002] In view of decreasing world crude oil reserves and the discussionabout the environmentally damaging consequences of the use of fossil andmineral fuels, there is increasing interest in alternative energysources based on renewable raw materials. These include in particularnatural oils and fats of vegetable or animal origin. These are generallytriglycerides of fatty acids which have from 10 to 24 carbon atoms and acalorific value comparable to conventional fuels, but are at the sametime classified as biodegradable and environmentally compatible.

[0003] Oils obtained from animal or vegetable material are mainlymetabolism products which include triglycerides of monocarboxylic acids,for example acids having from 10 to 25 carbon atoms, and correspond tothe formula

[0004] where R is an aliphatic radical which has from 10 to 25 carbonatoms and may be saturated or unsaturated.

[0005] In general, such oils contain glycerides from a series of acidswhose number and type vary with the source of the oil, and they mayadditionally contain phosphoglycerides. Such oils can be obtained byprocesses known from the prior art.

[0006] As a consequence of the sometimes unsatisfactory physicalproperties of the triglycerides, the industry has applied itself toconverting the naturally occurring triglycerides to fatty acid esters oflow alcohols such as methanol or ethanol. The prior art also includesmixtures of middle distillates with oils of vegetable or animal origin(also referred to hereinbelow as

biofuel oils”).

[0007] EP-B-0 665 873 discloses a fuel oil composition which comprises abiofuel, a fuel oil based on crude oil and an additive which comprises(a) an oil-soluble ethylene copolymer or (b) a comb polymer or (c) apolar nitrogen compound or (d) a compound in which at least onesubstantially linear alkyl group having from 10 to 30 carbon atoms isbonded to a nonpolymeric organic radical, in order to provide at leastone linear chain of atoms which includes the carbon atoms of the alkylgroups and one or more nonterminal oxygen atoms, or (e) one or more ofthe components (a), (b), (c) and (d).

[0008] A hindrance to the use of mixtures of middle distillates andbiofuel oils is their strong tendency to enter into stable emulsionswith water. Such emulsions result in corrosion problems in thedistribution chain of the fuel oils, and also when they are used inmotor vehicles.

[0009] It is therefore an object of this invention to find a suitabledemulsifier for mixtures of middle distillates and biofuel oils. It hasnow been found that, surprisingly, ethylene copolymers which containhydrophilic substituents are excellent demulsifiers for such mixtures.

[0010] The present invention provides a fuel oil comprising a majorproportion of a mixture of

[0011] A) a middle distillate fuel oil, and

[0012] B) a biofuel oil, and also a minor proportion of

[0013] C) an oil-soluble copolymer of ethylene and at least 0.2 to 35mol % of a further olefinically unsaturated compound which contains atleast one free hydroxyl group, and which has an OH number of from 10 to300 mg KOH/g.

[0014] The invention further provides the use of the copolymer definedunder C) as a demulsifier in mixtures of middle distillate fuel oilswith biofuel oils.

[0015] The invention further provides a method for demulsifying mixturesof middle distillate fuel oils with biofuel oils by adding theabove-defined copolymer to the mixtures.

[0016] As constituent A), middle distillate fuel oils are used. Thisrefers in particular to those mineral oils which are obtained bydistilling crude oil and boil in the range from 120 to 450° C., forexample kerosene, jet fuel, diesel and heating oil. Preference is givento using those middle distillates which contain less than 350 ppm ofsulfur, particularly preferably less than 200 ppm of sulfur, inparticular less than 50 ppm of sulfur and in special cases less than 10ppm of sulfur. These are generally those middle distillates which havebeen subjected to refining under hydrogenating conditions, and thereforecontain only small fractions of polyaromatic and polar compounds. Theyare preferably those middle distillates which have 95% distillationpoints below 370° C., in particular 350° C. and in special cases below330° C. The middle distillates preferably have aromatic contents ofbelow 28% by weight, in particular below 20% by weight.

[0017] As constituent B), biofuel oils are used. In a preferredembodiment, the biofuel oil, which is frequently also referred to as

biodiesel” or

biofuel” comprises fatty alkyl esters of fatty acids having from 14 to24 carbon atoms and alcohols having from 1 to 4 carbon atoms. Arelatively large proportion of the fatty acids commonly contains one,two or three double bonds. The fatty acids are more preferably, forexample, rapeseed oil methyl ester and especially mixtures whichcomprise rapeseed oil fatty acid methyl ester, sunflower oil fatty acidmethyl ester and/or soya oil fatty acid methyl ester.

[0018] Examples of oils which derive from animal or vegetable materialand which can be used in the inventive composition are rapeseed oil,coriander oil, soya oil, cottonseed oil, sunflower oil, castor oil,olive oil, groundnut oil, corn oil, almond oil, palm kernel oil, coconutoil, mustardseed oil, beef tallow, bone oil and fish oils. Furtherexamples include oils which derive from wheat, jute, sesame, sheatreenut, arachis oil and linseed oil, and can be derived from these byprocesses known from the prior art. It is also possible to use oilswhich have been obtained from used oils such as deep-frying oil.Rapeseed oil, which is a mixture of fatty acids partially esterifiedwith glycerol, is preferred, since it is obtainable in large amounts andis obtainable in a simple manner by extractive pressing of rapeseed. Inaddition, preference is likewise given to the widely available oils ofsunflowers and soya, and also to their mixtures with rapeseed oil.

[0019] Useful lower alkyl esters of fatty acids include the following,for example as commercial mixtures: the ethyl, propyl, butyl and inparticular methyl esters of fatty acids having from 12 to 22 carbonatoms, for example of lauric acid, myristic acid, palmitic acid,palmitoleic acid, stearic acid, oleic acid, elaidic acid, petroselicacid, ricinoleic acid, elaeostearic acid, linoleic acid, linolenic acid,eicosanoic acid, gadoleic acid, docosanoic acid or erucic acid, whichpreferably have an iodine number of from 50 to 150, in particular from90 to 125. Mixtures having particularly advantageous properties arethose which contain mainly, i.e. at least 50% by weight of, methylesters of fatty acids having from 16 to 22 carbon atoms and 1, 2 or 3double bonds. The preferred lower alkyl esters of fatty acids are themethyl esters of oleic acid, linoleic acid, linolenic acid and erucicacid.

[0020] Commercial mixtures of the type mentioned are obtained, forexample, by hydrolyzing and esterifying animal and vegetable fats andoils by transesterifying them with lower aliphatic alcohols. To preparelower alkyl esters of fatty acids, it is advantageous to start from fatsand oils having a high iodine number, for example sunflower oil,rapeseed oil, coriander oil, castor oil, soya oil, cottonseed oil,groundnut oil or beef tallow. Preference is given to lower alkyl estersof fatty acids based on a new variety of rapeseed oil of whose fattyacid component more than 80% by weight are derived from unsaturatedfatty acids having 18 carbon atoms.

[0021] The mixing ratio of the constituents A and B may vary as desired.It is preferably between A:B=99.9:0.1 and 0.1:99.9, in particular 99:1and 1:99, especially 95:5 and 5:95, for example 85:15 and 15:85 or 80:20and 20:80.

[0022] Constituent C) is an ethylene copolymer. In a preferredembodiment of the invention, the copolymer has an OH number of from 20to 250 mg KOH/g, in particular from 25 to 200 mg KOH/g. In a furtherpreferred embodiment, the copolymer has an average molecular weight Mwof from 700 to 10,000 g/mol.

[0023] The olefinically unsaturated compounds which are present in thecopolymer in addition to ethylene are preferably vinyl esters, acrylicesters, mono- and diesters of ethylenically unsaturated carboxylicacids, methacrylic esters, alkyl vinyl ethers and/or alkenes which bearhydroxyalkyl, hydroxyalkenyl, hydroxycycloalkyl or hydroxyaryl radicals.These radicals contain at least one hydroxyl group which may be in anydesired position on the radical, but preferably at the chain end(ω-position) or in the para-position in the case of ring systems.

[0024] The vinyl esters are preferably those of the formula 1

CH₂=CH-OCOR¹  (1)

[0025] where R¹ is C₁-C₃₀-hydroxyalkyl, preferably C₁-C₁₂-hydroxyalkyl,especially C₂-C₆-hydroxyalkyl, and also the corresponding hydroxyalkoxyradicals. Suitable vinyl esters include 2-hydroxyethyl vinyl esters,α-hydroxypropyl vinyl esters, 3-hydroxypropyl vinyl esters and4-hydroxybutyl vinyl esters, and also diethylene glycol monovinylesters.

[0026] The acrylic esters are preferably those of the formula 2

CH₂=CR²-COOR³  (2)

[0027] where R² is hydrogen or methyl and R³ is C₁-C₃₀-hydroxyalkyl,preferably C₁-C₁₂-hydroxyalkyl, especially C₂-C₆-hydroxyalkyl, and alsothe corresponding hydroxyalkoxy radicals. Suitable acrylic estersinclude hydroxyethyl acrylate, hydroxyethyl methacrylate,2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 3-hydroxypropylmethacrylate, hydroxyisopropyl acrylate, 4-hydroxybutyl acrylate andglycerol monoacrylate. Equally suitable are the corresponding esters ofmethacrylic acid, and also esters of ethylenically unsaturateddicarboxylic acids such as maleic acid, fumaric acid or itaconic acidwith diols.

[0028] The alkyl vinyl ethers are preferably compounds of the formula 3

CH₂═CH—OR⁴  (3)

[0029] where R⁴ is C₁-C₃₀-hydroxyalkyl, preferably C₁-C₁₂-hydroxyalkyl,especially C₂-C₆-hydroxyalkyl, and also the corresponding hydroxyalkoxyradicals. Suitable alkyl vinyl ethers include 2-hydroxyethyl vinylether, hydroxypropyl vinyl ether, hexanediol monovinyl ether,4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether andcyclohexanedimethanol monovinyl ether.

[0030] The alkenes are preferably monounsaturated hydroxyhydrocarbonshaving from 3 to 30 carbon atoms, in particular from 4 to 16 carbonatoms and especially from 5 to 12 carbon atoms. Suitable alkenes includedimethylvinylcarbinol (=2-methyl-3-buten-2-ol), allyloxypropanediol,2-butene-1,4-diol, 1-buten-3-ol, 3-buten-1-ol, 2-buten-1-ol,1-penten-3-ol, 1-penten-4-ol, 2-methyl-3-buten-1-ol, 1-hexen-3-ol,5-hexen-1-ol and 7-octene-1,2-diol.

[0031] Likewise suitable for use as demulsifiers are copolymerscontaining structural units which derive from ethylene and vinylalcohol. Copolymers of this type can be prepared by partially or fullyhydrolyzing a copolymer containing structural units which derive fromethylene and vinyl acetate.

[0032] Equally, copolymers which derive from ethylene and monomers whichbear glycidyl radicals, for example glycidyl (meth)acrylate or glycidylallyl ether, after hydrolysis with water, alcohols such as methanol orglycol, or amines, for example ammonia, methylamine, ethanolamine ordiethanolamine can be used in accordance with the invention.

[0033] Demulsification can also be achieved in the inventive manner byusing ethylene copolymers which contain alkoxylated acids groups.Ethylene copolymers suitable for this purpose are, for example, thosecontaining acrylic acid, methacrylic acid, itaconic acid, fumaric acid,maleic acid or maleic anhydride. To this end, these copolymerscontaining acid groups are alkoxylated on the acid groups with C₁- toC₁₀-alkylene oxides. Preferred alkylene oxides are ethylene oxide,propylene oxide and butylene oxide. The alkoxylation is preferablyeffected using from 0.5 to 10 mol, in particular from 1 to 5 mol andespecially from 1 to 2 mol, of alkylene oxide per mole of acid group.

[0034] The molar proportion of hydroxyl-functionalized comonomers in thecopolymer is preferably from 0.5 to 15%, in particular from 1 to 12%.

[0035] The melt viscosities of the copolymers according to the inventionat 140° C. are preferably below 10,000 mPas, in particular between 10and 1000 mPas and especially between 15 and 500 mPas.

[0036] In addition to ethylene, the copolymers according to theinvention contain at least one comonomer having hydroxyl groups. Theymay also contain further, for example one, two or three, furtherolefinically unsaturated comonomers. Such olefinically unsaturatedcomonomers are, for example, vinyl esters, acrylic acid, methacrylicacid, acrylic esters, methacrylic esters, vinyl ethers or olefins.Particularly preferred vinyl esters are vinyl acetate, vinyl propionateand vinyl esters of neocarboxylic acids having 8, 9, 10, 11 or 12 carbonatoms. Particularly preferred acrylic and methacrylic esters are thosewith alcohols having from 1 to 20 carbon atoms, in particular ofmethanol, ethanol, propanol, n-butanol, isobutanol and tert-butanol.Particularly preferred vinyl ethers are hydroxyvinyl ethers.Particularly preferred olefins are those having 3 to 10 carbon atoms,especially propene, isobutylene, diisobutylene, norbornene,4-methyl-pentene-1 and hexene. Particular preference is given toterpolymers of ethylene, a hydroxy-functionalized comonomer and eithervinyl acetate or a vinyl ester of a neocarboxylic acid having from 8 to12 carbon atoms. When the copolymers contain a further comonomer, itsmolar fraction is preferably up to 18%, in particular up to 12%.

[0037] The comonomers are copolymerized by known processes (on thissubject, cf., for example, Ullmanns Encyclopädie der Technischen Chemie,4^(th) edition, Vol. 19, pages 169 to 178). Suitable are polymerizationin solution, in suspension, in the gas phase and high-pressure bulkpolymerization. Preference is given to employing high-pressure bulkpolymerization which is carried out at pressures of from 50 to 400 MPa,preferably from 100 to 300 MPa, and temperatures of from 50 to 350° C.,preferably from 100 to 300° C. The reaction of the comonomers isinitiated by radical-forming initiators (radical chain initiators). Thissubstance class includes, for example, oxygen, hydroperoxides, peroxidesand azo compounds, such as cumene hydroperoxide, t-butyl hydroperoxide,dilauroyl peroxide, dibenzoyl peroxide, bis(2-ethylhexyl)peroxydicarbonate, t-butyl maleate, t-butyl perbenzoate, dicumylperoxide, t-butyl cumyl peroxide, di(t-butyl) peroxide,2,2′-azobis(2-methylpropanonitrile), 2,2′-azobis(2-methylbutyronitrile).The initiators are used individually or as a mixture of two or moresubstances in amounts of from 0.01 to 20% by weight, preferably from0.05 to 10% by weight, based on the comonomer mixture.

[0038] The desired melt viscosity of the copolymers for the givencomposition of the comonomer mixture is adjusted by varying the reactionparameters of pressure and temperature and optionally by addingmoderators. Useful moderators have been found to be hydrogen, saturatedor unsaturated hydrocarbons, e.g. propane, aldehydes, e.g.propionaldehyde, n-butyraldehyde or isobutyraldehyde, ketones, e.g.acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, oralcohols, e.g. butanol. Depending on the desired viscosity, themoderators are employed in amounts of up to 20% by weight, preferablyfrom 0.05 to 10% by weight, based on the comonomer mixture.

[0039] The high pressure bulk polymerization is carried out in knownhigh pressure reactors, for example autoclaves or tubular reactors,batchwise or continuously, and tubular reactors have proven particularlyuseful. Solvents such as aliphatic hydrocarbons or hydrocarbon mixtures,benzene or toluene may be present in the reaction mixture, although thesolvent-free procedure has been found to be particularly useful. In apreferred embodiment of the polymerization, the mixture of thecomonomers, the initiator and, if used, the moderator, is fed to atubular reactor via the reactor entrance and also via one or more sidebranches. The comonomer streams may have different compositions (EP-B-0271 738).

[0040] The copolymers C) are added to the mixtures comprising A) and B)in amounts of from 0.001 to 5% by weight, preferably from 0.005 to 1% byweight and especially from 0.01 to 0.05% by weight. They can be used assuch or else dissolved or dispersed in solvents, for example aliphaticand/or aromatic hydrocarbons or hydrocarbon mixtures, for exampletoluene, xylene, ethylbenzene, decane, pentadecane, petroleum fractions,kerosene, naphtha, diesel, heating oil, isoparaffins or commercialsolvent mixtures such as Solvent Naphtha, ®Shellsol AB, ®Solvesso 150,®Solvesso 200, ®Exxsol, ®Isopar and ®Shellsol D types. They arepreferably dissolved in fuel oil of animal or vegetable origin based onfatty acid alkyl esters. The additives according to the inventionpreferably contain 1-80%, especially 10-70%, in particular 25-60%, ofsolvent.

[0041] The copolymers C) can be added to the oil to be additized by themethods known from the prior art. When more than one copolymer componentis to be used, such components can be introduced into the oil togetheror separately in any desired combination.

[0042] To prepare additive packages for specific solutions to problems,the copolymers C) can also be used together with one or more oil-solublecoadditives which in themselves improve the properties of crude oils,lubricant oils or fuel oils. Examples of such coadditives are polarcompounds which effect paraffin dispersion (paraffin dispersants),alkylphenol-aldehyde resins, polymeric-cold flow improvers and alsooil-soluble amphiphiles.

[0043] For instance, it has been found that mixtures of the copolymersC) with those copolymers which contain from 10 to 40% by weight of vinylacetate and from 60 to 90% by weight of ethylene are outstandinglyuseful. In a further embodiment of the invention, the additivesaccording to the invention are used in a mixture with ethylene/vinylacetate/vinyl 2-ethylhexanoate terpolymers, ethylene/vinyl acetate/vinylneononanoate terpolymers and/or ethylene/vinyl acetate/vinylneodecanoate terpolymers to simultaneously improve the flowability andlubricity of mineral oils or mineral oil distillates. Apart fromethylene, the terpolymers of vinyl 2-ethylhexanoates, vinylneononanoates or of vinyl neodecanoates contain from 8 to 40% by weightof vinyl acetate and from 1 to 40% by weight of the respectivelong-chain vinyl ester. Apart from ethylene and from 10 to 40% by weightof vinyl esters and/or from 1 to 40% by weight of long-chain vinylesters, further preferred copolymers also contain from 0.5 to 20% byweight of olefin having from 3 to 10 carbon atoms, for exampleisobutylene, diisobutylene, propylene, methylpentene or norbornene.

[0044] The paraffin dispersants are preferably low molecular weight orpolymeric, oil-soluble compounds having ionic or polar groups, forexample amine salts, imides and/or amides. Particularly preferredparaffin dispersants contain reaction products of secondary fatty amineshaving from 8 to 36 carbon atoms, in particular dicoconut fatty amine,ditallow fatty amine and distearylamine. It has been found that paraffindispersants which are obtained by reacting aliphatic or aromatic amines,preferably long-chain aliphatic amines, with aliphatic or aromaticmono-, di-, tri- or tetracarboxylic acids or their anhydrides areparticularly useful (cf. U.S. Pat. No. 4,211,534). Other paraffindispersants are copolymers of maleic anhydride and α,β-unsaturatedcompounds, which may optionally be reacted with primary monoalkylaminesand/or aliphatic alcohols (cf. EP-A-0 154 177), the reaction products ofalkenyl-spiro-bislactones with amines (cf. EP-A-0 413 279 B1) and,according to EP-A-0 606 055 A2, reaction products of terpolymers basedon α,β-unsaturated dicarboxylic anhydrides, α,β-unsaturated compoundsand polyoxyalkylene ethers of lower unsaturated alcohols.

[0045] Suitable coadditives which effect paraffin dispersion are, forexample, esters. These esters derive from polyols having 3 or more OHgroups, in particular from glycerol, trimethylolpropane,pentaerythritol, and also the oligomers which can be obtained therefromby condensation and have from 2 to 10 monomer units, for examplepolyglycerol. The polyols have generally been reacted with from 1 to 100mol of alkylene oxide, preferably from 3 to 70 mol, in particular 5 to50 mol, of alkylene oxide per mole of polyol. Preferred alkylene oxidesare ethylene oxide, propylene oxide and butylene oxide. The alkoxylationis effected by known processes.

[0046] The fatty acids suitable for the esterification of thealkoxylated polyols preferably have from 8 to 50, in particular from 12to 30, especially from 16 to 26, carbon atoms. Suitable fatty acids are,for example, lauric acid, tridecanoic acid, myristic acid, pentadecanoicacid, palmitic acid, margaric acid, stearic acid, isostearic acid,arachic acid and behenic acid, oleic acid and erucic acid, palmitoleicacid, myristoleic acid, ricinoleic acid, and also the fatty acidmixtures obtained from natural fats and oils. Preferred fatty acidmixtures contain more than 50% of fatty acids having at least 20 carbonatoms. Preferably, less than 50% of the fatty acids for esterificationcontain double bonds, in particular less than 10%; they are especiallyvery substantially saturated. In this context, very substantiallysaturated means an iodine number of the fatty acid used of up to 5 g ofI per 100 g of fatty acid. The esterification can also be effectedstarting from reactive derivatives of fatty acids such as esters withlower alcohols (for example methyl or ethyl esters) or anhydrides.

[0047] To esterify the alkoxylated polyols it is also possible to usemixtures of the above fatty acids with fat-soluble, polybasic carboxylicacids. Examples of suitable polybasic carboxylic acids are dimer fattyacids, alkenylsuccinic acids and aromatic polycarboxylic acids, and alsotheir derivatives such as anhydrides and C₁- to C₅-esters. Preference isgiven to alkenylsuccinic acids and their derivatives with alkyl radicalshaving from 8 to 200, in particular from 10 to 50, carbon atoms.Examples are dodecenyl-, octadecenyl- and poly(isobutenyl)succinicanhydride. Preference is given to using the polybasic carboxylic acidsin minor proportions of up to 30 mol %, preferably from 1 to 20 mol %,in particular from 2 to 10 mol %.

[0048] Ester and fatty acid are used for the esterification, based onthe content of hydroxyl groups on the one hand and carboxyl groups onthe other hand, in a ratio of 1.5:1 to 1:1.5, preferably from 1.1:1 to1:1.1, in particular equimolar. The paraffin-dispersing action isparticularly marked when there is an acid excess of up to 20 mol %,especially up to 10 mol %, in particular up to 5 mol %.

[0049] The esterification is carried out by customary processes. It hasbeen found to be particularly useful to react polyol alkoxylate withfatty acid, optionally in the presence of catalysts, for examplepara-toluenesulfonic acid, C₂- to C₅₀-alkylbenzenesulfonic acids,methanesulfonic acid or acidic ion exchangers. The water of reaction canbe removed distillatively by direct condensation or preferably by meansof azeotropic distillation in the presence of organic solvents, inparticular aromatic solvents, such as toluene, xylene or elsehigher-boiling mixtures such as ®Shellsol A, Shellsol B, Shellsol AB orSolvent Naphtha. Preference is given to esterifying to completion, i.e.using from 1.0 to 1.5 mol of fatty acid per mole of hydroxyl groups forthe esterification. The acid number of the esters is generally below 15mg KOH/g, preferably below 10 mg KOH/g, especially below 5 mg KOH/g.

[0050] Particularly preferered paraffin dispersants are prepared byreacting compounds which contain an acyl group with an amine. This amineis a compound of the formula NR⁶R⁷R⁸ where R⁶, R⁷ and R⁸ may be the sameor different, and at least one of these groups is C₈-C₃₆-alkyl,C₆-C₃₆-cycloalkyl, C₈-C₃₆-alkenyl, in particular C₁₂-C₂₄-alkyl,C₁₂-C₂₄-alkenyl or cyclohexyl, and the remaining groups are eitherhydrogen, C₁-C₃₆-alkyl, C₂-C₃₆-alkenyl, cyclohexyl, or a group of theformulae -(A-O)_(x)-E or -(CH₂)_(n)-NYZ, where A is an ethylene orpropylene group, x is a number from 1 to 50, E=H, C₁-C₃₀-alkyl,C₅-C₁₂-cycloalkyl or C₆-C₃₀-aryl, and n is 2, 3 or 4, and Y and Z areeach independently H, C₁-C₃₀-alkyl or -(A-O)_(x). In this context, anacyl group is a functional group of the following formula:

>C=O

[0051] The paraffin dispersants can be admixed with the copolymers C) oradded separately to the middle distillate to be additized.

[0052] Alkylphenol-aldehyde resins are known in principle and described,for example, in Römpp Chemie Lexikon, 9th edition, Thieme Verlag1988-92, Volume 4, p. 3351ff. The alkyl or alkenyl radicals of thealkylphenol have 6-24, preferably 8-22, in particular 9-18, carbonatoms. They may be linear or preferably branched, and the branch maycontain secondary and also tertiary structures. They are preferably n-and isohexyl, n- and isooctyl, n- and isononyl, n- and isodecyl, n- andisododecyl, tetradecyl, hexadecyl, octadecyl, eicosyl and alsotripropenyl, tetrapropenyl, pentapropenyl and polyisobutenyl up to C₂₄.The alkylphenol-aldehyde resin may also contain up to 20 mol % of phenolunits and/or alkylphenols having short alkyl chains, for examplebutylphenol. For the alkylphenol-aldehyde resin, identical or differentalkylphenols may be used.

[0053] The aldehyde in the alkylphenol-aldehyde resin has from 1 to 10,preferably from 1 to 4, carbon atoms, and may bear further functionalgroups. It is preferably an aliphatic aldehyde, more preferablyformaldehyde.

[0054] The molecular weight of the alkylphenol-aldehyde resins ispreferably 350-10 000, in particular 400-5000 g/mol. This preferablycorresponds to a degree of condensation n of from 3 to 40, in particularfrom 4 to 20. A prerequisite is that the resins are oil-soluble.

[0055] In a preferred embodiment of the invention, thesealkylphenol-formaldehyde resins are those which are oligomers orpolymers having a repeating structural unit of the formula

[0056] where R^(A) is C₆-C₂₄-alkyl or -alkenyl, R^(B) is OH orO-(A-O)_(x)-H where A=C₂-C₄-alkylene and x=1 to 50, and n is a numberfrom 2 to 50, in particular from 5 to 40.

[0057] The alkylphenol-aldehyde resins are prepared in a known manner bybasic catalysis to give condensation products of the resol type, or byacidic catalysis to give condensation products of the novolak type.

[0058] The condensates obtained in both ways are suitable for thecompositions according to the invention. Preference is given to thecondensation in the presence of acidic catalysts.

[0059] To prepare the alkylphenol-aldehyde resins, an alkylphenol having6-24, preferably 8-22, in particular 9-18, carbon atoms per alkyl group,or mixtures thereof, are reacted with at least one aldehyde, using about0.5-2 mol, preferably 0.7-1.3 mol and in particular equimolar amounts ofaldehyde, per mole of alkylphenol compound.

[0060] Suitable alkylphenols are in particular n- and isohexylphenol, n-and isooctylphenol, n- and isononylphenol, n- and isodecylphenol, n- andisododecylphenol, tetradecylphenol, hexadecylphenol, octadecylphenol,eicosylphenol, tripropenylphenol, tetrapropenylphenol andpoly(isobutenyl)phenol up to C₂₄.

[0061] The alkylphenols are preferably para-substituted. Thealkylphenols may bear one or more alkyl radicals. The proportionsubstituted by more than one alkyl group is preferably at most 5 mol %,in particular at most 20 mol % and especially at most 40 mol %. At most40 mol %, in particular at most 20 mol %, of the alkylphenols usedpreferably bear an alkyl radical in the ortho-position. Especially, thealkylphenols are unsubstituted by tertiary alkyl groups in theortho-position to the hydroxyl group.

[0062] The aldehyde may be a mono- or dialdehyde and bear furtherfunctional groups such as -COOH. Particularly suitable aldehydes areformaldehyde, acetaldehyde, butyraldehyde, glutaraldehyde and glyoxalicacid, preferably formaldehyde. The formaldehyde may be used in the formof paraformaldehyde or in the form of a preferably 20-40% by weightaqueous formalin solution. It is also possible to use correspondingamounts of trioxane.

[0063] Alkylphenol is customarily reacted with aldehyde in the presenceof alkaline catalysts, for example alkali metal hydroxides oralkylamines, or of acidic catalysts, for example inorganic or organicacids, such as hydrochloric acid, sulfuric acid, phosphoric acid,sulfonic acid, sulfamido acids or haloacetic acids, and effected in thepresence of an organic solvent which forms an azeotrope with water, forexample toluene, xylene, higher aromatics or mixtures thereof. Thereaction mixture is heated to a temperature of from 90 to 200° C.,preferably 100-160° C., and the water of reaction formed is removedduring the reaction by azeotropic distillation. Solvents which releaseno protons under the conditions of the condensation can remain in theproducts after the condensation reaction. The resins may be useddirectly or after neutralization of the catalyst, optionally afterfurther dilution of the solution with aliphatic and/or aromatichydrocarbons or hydrocarbon mixtures, for example petroleum fractions,kerosene, decane, pentadecane, toluene, xylene, ethylbenzene or solventssuch as ®Solvent Naphtha, ®Shellsol AB, ®Solvesso 150, ®Solvesso 200,®Exxsol, ®ISOPAR and ®Shellsol D types.

[0064] Finally, in a further embodiment of the invention, the additivesaccording to the invention are used together with comb polymers. Thisrefers to polymers in which hydrocarbon radicals having at least 8, inparticular at least 10, carbon atoms are bonded to a polymer backbone.These are preferably homopolymers whose alkyl side chains have at least8 and in particular at least 10 carbon atoms. In copolymers, at least20%, preferably at least 30%, of the monomers have side chains (cf.Comb-like Polymers—Structure and Properties; N. A. Platé and V. P.Shibaev, J. Polym. Sci. Macromolecular Revs. 1974, 8, 117 ff). Examplesof suitable comb polymers are, for example, fumarate/vinyl acetatecopolymers (cf. EP 0 153 76 A1), copolymers of a C₆-C₂₄-α-olefin and anN-C₆-C₂₂-alkylmaleimide (cf. EP-A-0 320 766), and also esterifiedolefin/maleic anhydride copolymers, polymers and copolymers of α-olefinsand esterified copolymers of styrene and maleic anhydride.

[0065] Comb polymers can be described, for example, by the formula

[0066] In this formula: A is R′, COOR′, OCOR′, R″-COOR′ or OR′; D is H,CH₃, A or R; E is H or A; G is H, R″, R″-COOR′, an aryl radical or aheterocyclic radical; M is H, COOR″, OCOR″, OR″ or COOH; N is H, R″,COOR″, OCOR, COOH or an aryl radical; R' is a hydrocarbon chain having8-150 carbon atoms; R'' is a hydrocarbon chain having from 1 to 10carbon atoms; m is a number between 0.4 and 1.0; and n is a numberbetween 0 and 0.6.

[0067] The mixing ratio (in parts by weight) of the copolymers C) withpolymeric cold flow improvers, paraffin dispersants, comb polymers andresins is in each case from 1:10 to 20:1, preferably from 1:1 to 10:1.

[0068] The copolymers C) can be used alone or else together with otheradditives, for-example with other solidification point depressants ordewaxing auxiliaries, with corrosion inhibitors, antioxidants, lubricityadditives, sludge inhibitors, dehazers and additives for lowering thecloud point.

EXAMPLES

[0069] Characterization of the Test Oils:

[0070] The CFPP value is determined in accordance with EN 116, theboiling characteristics in accordance with ASTM D-86 and the cloud pointin accordance with ISO 3015. TABLE 1 Analysis of the biodiesel used(also referred to hereinbelow as “RME”) Chain lengths Fraction Firstrunnings 0.12 C₁₂ 0.01 C₁₃ + iso C₁₄ 0.01 C₁₄: 0 0.05 C₁₄: 1 0.0 C₁₅ +iso-C₁₆ 0.05 C₁₆: 0 4.64 C₁₆: 1/2/3 0.28 C₁₇ + iso-C₁₈ 0.11 C₁₈: 0 0.37C18: 1 trans + cis 61.72 C₁₈: 2 trans + cis 19.16 C₁₈: 3 9.01 C₁₉ +iso-C₂₀ 0.29 C₂₀: 0 0.70 C₂₀: 1/2/3 1.57 C₂₁ + iso C₂₂ 0.26 C₂₂: 0 0.36C₂₂: 1/2/3 0.39 C₂₄ 0 0.15 C₂₃ + iso C₂₄ 0.16 C₂₄: 1/2/3 0.18 Finalrunnings 0.41 100.00 Iodine number calculated from GC 116

[0071] TABLE 2 Characterization of the middle distillates used F1 F2 F3F4 Sulfur content, ppm 7.9 4.9 32.0 900 Density, g/cm³ 0.8436 0.83060.8348 0.8487 Initial boiling point, ° C. 209.9 143.9 209.1 203.7 Finalboiling point, ° C. 334.6 363.2 347.8 365.6 Boiling range (90-20), 63.587.6 83.8 94.9 ° C. Aromatics content, % by 25.7 16.5 20.5 29.9 wt.

[0072] Characterization of the Copolymers

[0073] The following copolymers were used: P1 E/VA/4-hydroxybutyl vinylether (4-HBVE) terpolymer P2 E/VeoVa-10/hydroxypropyl acrylate (HPA)terpolymer P3 E/VA/hydroxybutyl vinyl ether (HBVE) terpolymer P4E/VA/hydroxybutyl vinyl ether (HBVE) terpolymer P5E/VA/Hydroxyethylvinylether (HEVE)-Terpolymer P6 E/VA/hydroxypropylmethacrylate terpolymer P7 E/VA/2-methyl-3-buten-2-ol terpolymer P8 E/VAcopolymer P9 E/VA/VeoVa10 terpolymer P10 E/VA/VeoVa10 terpolymer

[0074] For the purposes of the present invention, the OH numbers aredetermined in accordance with DIN 53240 by reacting with a definedamount of excess acetic anhydride and subsequently titrating the aceticacid formed. TABLE 3 Characterization of the copolymers Contents in % bywt. Of Vinyl VeoVa Hydroxy Polymer acetate 10 comonomer V₁₄₀, mPa · s OHnumber P1 29.1 — 4.2 53 20 P2 — 23.6 34.8 135 121 P3 22.2 — 13.7 88 66P4 24.1 — 7.3 99 35 P5 21 — 11.5 96 71 P6 11.3 — 36.6 169 112 P7 26.4 —0.77 131 5 P8 32 — — 125 0 P9 31 8 — 110 0 P10 31.5 4.1 — 170 0

[0075] Effectiveness as a Demulsifier

[0076] The Emulsification Tendency of Additives is Tested in Accordancewith ASTM

[0077] D 1094-85. 80 ml of a diesel fuel are admixed in a 100 mlmeasuring cylinder with 250 ppm of the additive to be tested and heatedto 60° C. for 15 minutes and then agitated. After cooling to roomtemperature, 20 ml of buffer solution are added and the cylinder isagitated for 2 minutes. After 5 minutes, the sample is assessed visuallyby the following criteria: Assessment of the separation layer Assessmentof the phase separation 1 Clear and clean 1 Complete absence of allemulsions and/or 1b small, clear bubbles which are estimated notdeposits in both phases or on the top of to cover more than 50% of theseparating the oil phase. layer. No streaks, no film formation or other2 As (1), but additionally small air bubbles or wetting on theseparating layer. small water droplets in the oil phase. 2 Streaks, filmformation or other wetting on the 3 Emulsions and/or deposits in bothphases separating layer or on the top of the oil phase, and/or drops 3Narrow border or slight foam formation, or in the water phase oradhering to the wall both (excluding the wall above the oil phase). In 4Thick border or extensive foam formation, or brackets: amount of thewater phase both

[0078] TABLE 4 Effectiveness of copolymers as a demulsifier in a mixtureof 95% by weight of F2 and 5% by weight of biodiesel visual assessmentActive Ex. Separation Water ingredient No. Copolymer layer Phaseseparation Oil phase phase dosage ppm  1 (C) none 3-4 14 ml 3 cloudyclear —  2 (C) P8 3 18 ml 3 cloudy clear 250  3 (C) P9 4 16 ml 3 cloudyclear 250  4 (C) P10 3 18 ml 3 cloudy clear 250  5 P1 1b* 20 ml 3 cloudyclear 250  6 P2 1* 20 ml 3 cloudy clear 250  7 P3 1* 20 ml 3 cloudyclear 250  8 P6 1* 20 ml 3 cloudy clear 250  9 P7 1* 20 ml 3 cloudyclear 250 10 P3 1* 20 ml 3 cloudy clear 250 11 P3 1* 20 ml 3 cloudyclear 100 12 P3 1* 20 ml 3 cloudy clear 50 13 P3 1* 20 ml 3 cloudy clear25 14 P3 1* 20 ml 3 cloudy clear 10 15 P6 1* 20 ml 3 cloudy clear 250 16P6 1b* 20 ml 3 cloudy clear 100 17 P6 1b* 20 ml 3 cloudy clear 50 18 P61b 20 ml 3 cloudy clear 25 19 P6 2 20 ml 3 cloudy clear 10 20 P2 1* 20ml 3 cloudy clear 250 21 P2 1b* 20 ml 3 cloudy clear 50 22 P7 1b* 20 ml3 cloudy clear 250 23 P7 1b* 20 ml 3 cloudy clear 50

[0079] TABLE 5 Influence of different mixing ratios between middledistillate and biofuel on the emulsification performance visualassessment Middle Phase Amount of water Water Active ingredient Exampledistillate Biofuel Copolymer Separation layer separation phase Oil phasephase dosage ppm 24 (C) 90% F1 10% — 3-4 3  8 ml cloudy clear — 25 (C)95% F1 5% — 1b 3 20 ml cloudy clear — 26 90% F1 10% P3 1 3 20 ml cloudyclear 10 27 (C) 90% F2 10% — 3-4 3  8 ml cloudy clear — 28 (C) 95% F2 5%— 3-4 3 14 ml cloudy clear — 29 90% F2 10% P3 1-2 3 20 ml cloudy clear10 relatively large clear air bubbles 30 (C) 90% F3 10% — 4 3 15 mlcloudy clear — 31 (C) 95% F3 5% — 4 3 10 ml cloudy clear — 32 90% F3 10%P3 1-2 3 20 ml cloudy clear 10 relatively large clear air bubbles

[0080] Influence of the Copolymer Containing Hydroxyl Groups on theAction of Cold Flow Improvers

[0081] A middle distillate having a CFPP of −7° C. and its mixture with5% of the biofuel described (CFPP of the mixture likewise −7° C.) withcold flow improver and copolymer containing hydroxyl groups wereinvestigated. TABLE 6 Influence on the cold flow properties bycopolymers containing hydroxyl groups Copolymers 300 300 ppm 300 ppm 300ppm ppm P8 + 10 ppm P9 + 10 ppm Example Fuel oil P8 P9 P4 P4 33 (C)Middle −16 −15 −17 −17 distillate 34 Middle −17 −16 −17 −16 distillate +biofuel

[0082] Influence of the Copolymers Containing Hydroxyl Groups on theEmulsification Performance of the Diesel/Biodiesel Mixture in thePresence of Flow Improvers

[0083] The emulsification performance of the oil F4 with the addition of5% by weight of biofuel was distinctly altered by adding 10 ppm of P4and exhibited hardly any emulsification tendency despite the presence of300 ppm of a flow improver. TABLE 7 Influence of cold flow improvers onthe emulsification tendency with and without copolymer C) visualassessment Active Sepa- ingredient ration Phase Oil Water dosage Ex. Oillayer separation phase phase ppm 35 (C) F4 1b 20 ml 3 cloudy clear — 36(C) F4 + RME 3 18 ml 3 cloudy clear — 37 F4 + RME 1* 20 ml 3 cloudyclear 10 38 (C) F4 + RME 3 18 ml 3 cloudy clear 250 39 F4 + RME 1b 20 ml3 cloudy clear 10 40 (C) F4 + RME 3 18 ml 3 cloudy clear 250 41 F4 + RME1b 20 ml 3 cloudy clear 10

1. A fuel oil comprising a major proportion of a mixture of A) a middledistillate fuel oil, and B) a biofuel oil, and a minor proportion of C)an oil-soluble copolymer of ethylene and at least 0.2 to 35 mol % of afirst comonomer, wherein the first comonomer is an olefinicallyunsaturated compound containing at least one free hydroxyl group, andhaving an OH number of from 10 to 300 mg KOH/g.
 2. A fuel oil as claimedin claim 1, wherein the A):B) mixing ratio is from 99:1 to 1:99.
 3. Afuel oil as claimed in claim 1, wherein the OH number of the oil-solublecopolymer C) is between 20 and
 250. 4. A fuel oil as claimed in claim 1,wherein the copolymer C) has an average molecular weight of from 700 to10,000 g/mol.
 5. A fuel oil as claimed in claim 1, wherein theproportion of the olefinically unsaturated compound in the copolymer C)is between 0.5 and 15 mol %.
 6. A fuel oil as claimed in claim 1,wherein the copolymer C) further comprises at least one second comonomerselected from the group consisting of vinyl esters, acrylic acid,methacrylic acid, acrylic esters, methacrylic esters, vinyl ethers andolefins.
 7. A fuel oil as claimed in claim 1, wherein the content of C)in the fuel oil is from 0.001 to 5% by weight.
 8. A fuel oil as claimedin claim 1, further comprises at least one alkylphenol-formaldehyderesin of the formula

where R^(A) is C₆-C₂₄-alkyl or -alkenyl, R^(B) is OH or O-(A-O)_(x)-Hwhere A=C₂-C₄-alkylene and x=1 to 50, and n is a number from 2 to
 50. 9.A method for demulsifing a mixture of at least one middle distillatefuel oil and at least one biofuel oil comprising the step of adding thethe mixture an oil-soluble copolymer of ethylene and at least 0.2 to 35mol % of a further olefinically unsaturated compound having at least onefree hydroxyl group and having an OH number of from 10 to 300 mg KOH/g.10. A fuel oil as claimed in claim 8, wherein n is from 5 to 40.